Chapter 1 - Orbit Determination Concepts

Abstract

This chapter discusses orbit determination concepts. The treatment presented in the chapter covers the fundamentals of satellite orbit determination and its evolution over the past four decades. Satellite orbit determination means the process by which one obtains knowledge of a satellite's motion relative to the center of mass of the Earth in a specified coordinate system. Orbit determination for celestial bodies has been a general concern of astronomers and mathematicians since the beginning of civilization and indeed has attracted some of the best analytical minds to develop the basis for much of the fundamental mathematics. Orbit determination methodology can be separated into two general classes: classical (or deterministic) orbit determination and modern (or statistical based) orbit determination. In the classical approach, observational errors are not considered and the problem is reduced to making the necessary number of measurements to determine the orbit. The modern orbit determination problem recognizes the influence of observation errors and, to minimize the effects of the observational error, more observations are used than the number of parameters to be estimated.